Related Field
The present invention relates to a reel-up and a method for winding into a roll a paper web and for starting a new roll.
Description of Related Art
During winding of paper webs to rolls in a reel-up of a paper machine, the paper web that arrives from a drying cylinder in a paper making machine is caused to be wound on reel spools to form paper rolls. When a paper roll has been completed, newly arriving paper web must be caused to switch to a new reel spool such that a new paper roll can be wound on the new paper roll. This operation of changing to a new reel spool is known as turn-up.
Several different methods have been proposed for changing over between a completed reel and a new reel. One method that has been proposed to cut a narrow tail at one side of the web which tail is initially wound on the old roll. In this context, a “tail” means a narrow strip which has been cut from the paper web and which tail is narrower than the full width paper web. A new reel spool is moved towards the narrow tail and glue is applied to the narrow tail or to the reel spool such that the narrow tail is caused to adhere to the new reel spool whereafter the tail is widened to full width. When the tail is caused to adhere to the new reel spool, the tail is ripped off such that it is no longer wound onto the old paper roll. In this known method, the time lost for the change may typically be on the order of about 10-15 seconds. A disadvantage with this method is that the new paper roll will inevitably be somewhat thicker at that end of the new reel spool where the narrow tail is first caused to adhere. At the opposite end of the new reel spool, the paper web may become more loosely wound.
Another known method is to use reel spools that have been provided with adhesive tape in advance. A problem with this method is that the reel spools become more difficult to handle.
Another known method is “balloon blowing”. Balloon blowing entails creating slack across the full width of the web by somewhat retarding the finished reel. With the aid of compressed air, the fold thus formed is then forced into the nip between the new reel shaft and the reel drum, after which the web is cut off. In order to increase the reliability of this type of reel switching, glue may also be applied to the reel spool or to the paper web. Experience has showed that the reliability of balloon blowing is low, in about 50%-60% of the cases, the switch is successful. When the operation is unsuccessful, a new attempt must be made.
Another method that has been suggested is to use a beam that supports glue nozzles distributed over the widths of the web. A solution in which glue nozzles are used is disclosed in U.S. Pat. No. 6,805,317.
Yet another known way of achieving turn-up is to cut the paper web by means of water jets. This method can take somewhat different forms but entails two water nozzles that are used to cut a narrow tail in the middle of the paper web and a nozzle for glue is used to apply glue to the new reel spool at the middle of the new reel spool where the narrow tail meets the new reel spool. The water nozzles are then moved toward the edges of the paper web such that the narrow tail is made wider and finally reaches full width. Examples of such a solution are disclosed in for example WO 97/48632 and U.S. Pat. No. 5,360,179. This method is sometimes referred to as “water jet turn-up”.
In recent years, a new kind of reel-up has been suggested in which reeling is made against an endless flexible member instead of against a pressure roll. Such a reel-up is disclosed in for example U.S. Pat. No. 5,901,918 and reel-ups of this type have produced very good results, especially for tissue paper grades.
It is an object of the present invention to provide good solution for the turn-up operation in a reel-up in which winding is made against an endless flexible member, i.e. a reel-up of the kind disclosed in U.S. Pat. No. 5,901,918.